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/*************************************************************************
 * @file 
 * Base64 tool.
 ************************************************************************/
/*************************************************************************
 * Change History
 * 2005-01-02 create this file.
 * 2005-02-28 make Encode_(...) to be inline for speed.
 ************************************************************************/
#include	"xfbase64.hxx"

const  sal_Char aBase64EncodeTable[] =
{ 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/' };

/**
 * @descr	Encode 3 byte to 4 byte.
 *			Please refer to RFC to get the base64 algorithm.
 */
inline void	Encode_(sal_uInt8 *src, sal_Char* dest)
{
	sal_Int32 nBinaer = (((sal_uInt8)src[ 0]) << 16) +
		(((sal_uInt8)src[1]) <<  8) +
		((sal_uInt8)src[2]);
	
	sal_uInt8 nIndex = ((nBinaer & 0xFC0000) >> 18);
	dest[0] = aBase64EncodeTable [nIndex];
	
	nIndex = (nBinaer & 0x3F000) >> 12;
	dest[1] =aBase64EncodeTable [nIndex];
	
	nIndex = (nBinaer & 0xFC0) >> 6;
	dest[2] = aBase64EncodeTable [nIndex];
	
	nIndex = (nBinaer & 0x3F);
	dest[3] = aBase64EncodeTable [nIndex];
}

/**
 * @descr	Base64 encode.
 */
rtl::OUString XFBase64::Encode(sal_uInt8 *buf, sal_Int32 len)
{
	sal_Char	*buffer;
	sal_Int32	nNeeded;
	sal_Int32	cycles = len/3;
	sal_Int32	remain = len%3;
	
	if( remain == 0 )
		nNeeded = cycles*4;
	else
		nNeeded = (cycles+1)*4;
	buffer = new sal_Char[nNeeded+1];
	
	rtl_zeroMemory(buffer,nNeeded+1);

	for( sal_Int32 i=0; i<cycles; i++ )
		Encode_(buf+i*3,buffer+i*4);
	
	sal_uInt8 last[3];
	if( remain == 1 )
	{
		last[0] = buf[len-1];
		last[1] = last[2] = 0;
		Encode_(last,buffer+nNeeded+1-5);
	}
	else if( remain == 2 )
	{
		last[0] = buf[len-2];
		last[1] = buf[len-1];
		last[2] = 0;
		Encode_(last,buffer+nNeeded+1-5);
	}

	rtl::OUString str = rtl::OUString::createFromAscii(buffer);
	delete[] buffer;
	
	return str;
}